In certain applications it is necessary to coordinate or synchronize the closure of a circuit breaker with the functioning of other electrical apparatus, such as generators. With the typical industrial circuit breaker, charging of its mechanism springs preparatory to closure of its contacts is achieved by articulation of a manual operating handle. Normally, it is impossible to predict with any degree of precision when, after the mechanism springs have become fully charged, the mechanism has reached the condition where the springs can discharge pursuant to powering the breaker movable contacts to their closed circuit positions in engaging relation with the breaker stationary contacts. For the traditional toggle-type breaker operating mechanism, this condition is reached when, during mechanism articulation, the line of action of the mechanism springs moves from one side to the other side of a particular toggle pivot point.
To provide rather precise control of the moment of closure of breaker contacts, a hook has been used to hold the breaker movable contacts in their open positions against the bias of the mechanism springs, despite the fact that the breaker mechanism has been articulated to its contact closure condition. When contact closure is desired, the hook is simply articulated to release the breaker movable contacts which then abruptly spring to their closed positions under the urgence of the mechanism springs. It is seen that in this arrangement, the circuit breaker has three stable conditions, that is, the circuit breaker may be not only open or closed, but also charged and ready to be closed. Since the breaker operating handle typically cannot distinctively indicate by its position each of these three breaker conditions, it is highly desirable to provide a separate indicator mechanism operable to unambiguously identify whether the breaker is open, closed or charged and ready to close. Commonly assigned, U.S. Pat. No. 4,042,896 discloses the utilization of a hook to hold breaker movable contacts open while the breaker mechanism is charged and indicator apparatus to identify these various conditions assumed by the circuit breaker.
It is a principal object of the present invention to provide simplified and cost-improved apparatus for controlling the closure of circuit breaker contacts and for indicating the circuit breaker condition.
A further object of the present invention is to provide circuit breaker contact closure control and condition indicator apparatus of the above character which is inexpensive to manufacture, compact, and reliable in operation.
Other objects of the invention will in part be obvious and in part appear hereinafter.